1. Field of the Invention
The present invention relates to an airdrop type buoy apparatus, which is dropped to a war surface of sea or lake by a flight vehicle, such as aircraft that is flying in the air, to be floated as a marker, a hydrographic conditions measuring device or the like, and particularly, relates to an airdrop type buoy apparatus for flexibly coping with a shock at the time of landing on the water to absorb the landing shock on a balloon and also suppressing the rise of an inner pressure of the balloon so that the balloon is hardly to burst.
2. Description of the Related Art
As disclosed in Japanese Unexamined Patent Publication No. 2000-128087, such a conventional type airdrop type buoy apparatus that is dropped by a flight vehicle flying in the air to be floated on the water of sea or lake, comprises: a balloon which lets air therein at an opening thereof while falling, to expand, decreases a falling speed thereof to a speed at which a burst due to an aerodynamic load and a shock at the time of landing on the water does not occur, and then lands on the water to thereby function as a marker, and a container which is connected to the opening of the balloon to house the balloon therein, falls to introduce air to the opening of the balloon and also to function as a plumb bob; arm drawing means for drawing the balloon out of the container.
However, in such a conventional airdrop type buoy apparatus, the container functioning as the plumb bob is connected to the opening of the balloon, and thus the balloon that lets air therein via the opening to ed during falling in the air, and the container (plumb bob) are directly connected to each other to be integrated. Therefore, for example, when the container lands on the water of sea, a shock at the time of landing acting on the container also acts an the balloon directly. Further, when such a landing shock acts on the container, the balloon is dragged into the water due to inertia of the container. As a result a lower part of the balloon receives a water pressure to be deformed so that an inner pressure of the balloon rises abruptly.
Thus, according to the conventional airdrop type buoy apparatus, since the landing shock directly acts on the balloon and the inner pressure of the balloon rises abruptly when landing, there is a possibility that the balloon burst when landing. Then, if burst, the balloon cannot function as the marker after landing. In order to avoid such a situation, there is a necessity to form the balloon in solid. However, if the thickness of film material or the structural intensity of balloon is increased, there is a possibility of increase in weight and size, and further the rise of manufacturing cost.
The present invention has been accomplished in view of the problems as described above and has an object to provide an airdrop type buoy apparatus for flexibly coping with a shock at the time of landing on the water to absorb the landing shock on a balloon and also for suppressing the rise of an inner pressure of the balloon so that the balloon is hardly to burst.
In order to achieve the above object, an airdrop type buoy apparatus according to one aspect of the present invention, which is dropped by a flight vehicle flying in the air, and during failing, decreases a falling speed thereof to a predetermined speed while expanding, and then lands on the water to be floated, comprises: a balloon provided, at a lower end opening thereof, with an annular member for introducing air into the balloon when falling, for letting air therein via the annular member to expand to hold a three-dimensional shape after landing; a suspension rope connected to the annular member of the balloon at one end portion thereof and having flexibility to extend by a predetermined length; and a plumb bob connected to the other end portion of the suspension rope to serve as a plummet at the time of falling and landing of the balloon.
With the above constitution, the balloon and the plumb bob are connected to each other via the suspension rope having the flexibility to extend by the predetermined length. Thus, when the plumb bob lands on the water, since the suspension rope loosens, it becomes possible to flexibly cope with a shock at the time of landing to absorb the landing shock on the balloon, and also to suppress the rise of an inner pressure of the balloon so that the balloon is hardly to burst. Consequently, it is unnecessary to form the balloon in solid differently from the conventional technique, thereby enabling to reduce the weight and size, and also the manufacturing cost of the balloon.
Further, an airdrop type buoy apparatus according to another aspect of the present invention, which is dropped by a flight vehicle flying in the air, and during failing, decreases a falling speed thereof to a predetermined speed while expanding, and then lands on the water to be floated, comprises: a balloon provided, at a lower end opening hereof, with an annular member for introducing air into the balloon when falling, for letting air therein via the annular member to expand to hold a three-dimensional shape or landing; a suspension rope connected to the annular member of the balloon at one end portion thereof and having flexibility to extend by a predetermined length; a plumb bob connected to the other end portion of the suspension rope to serve as a plummet at the time of falling and landing of the balloon; and a container housing therein a combination of the balloon, suspension rope and plumb bob, and accessories thereof, to be delivered for dropping.
With such a constitution, the combination of the balloon, suspension rope and plumb bob, and the accessories thereof are housed in the container, to be delivered for dropping. Thus, it becomes possible that the airdrop type buoy apparatus is loaded on the flight vehicle, such as aircraft to be delivered, and dropped to a required water surface as a marker, a hydrographic conditions measuring device or the like.
Other objects, characteristics and advantages of the present invention will become apparent from the following description of embodiments, in conjunction with the appended drawings.